This invention relates to lithography and, in particular, to a pin registration system for use in recording a developable latent image upon a sensitized lithographic plate.
In one form of lithography, a photographic negative of the original subject matter to be reproduced is prepared in advance and the image bearing negative then positioned upon a strip sheet to create a desired format. Portions of the sheet are stripped or cut away about the imaged areas and the sheet then placed over a sensitized plate and the plate exposed through the sheet to record a developable latent image of the original upon the plate.
Typically, the edges of the strip sheet are used as reference planes from which the photonegative or negatives are located during the layout processes. However, the margins of the strip sheet do not have a direct correlation with the sensitized plate and, as a consequence, a good deal of time and effort is expended on positioning the information on the strip sheet so that it will ultimately be recorded at a desired location on the plate. The accuracy attained in preparing the lithographic plate is to a large extent dependent upon the skill and experience of the operator. As such, the procedure is subject to human error. When the procedure is complex, as in the case of the well-known step and repeat technique wherein two identical images of the original are recorded on a single plate, the chances of a human error happening are considerably increased.